package com.sakura.java8.stream;

import com.sakura.java8.stream.pojo.Employee;
import com.sakura.java8.stream.pojo.Employee.Status;
import org.junit.Test;

import java.util.*;
import java.util.stream.Collectors;
import java.util.stream.Stream;

/**
 * @Author Sakura
 * @Date 2022/11/7 18:07
 * @Version 1.0
 */
public class LearnStreamaAPI3 {


    List<Employee> emps = Arrays.asList(
            new Employee(102, "李四", 79, 6666.66, Status.BUSY),
            new Employee(101, "张三", 18, 9999.99, Status.FREE),
            new Employee(103, "王五", 28, 3333.33, Status.VOCATION),
            new Employee(104, "赵六", 8, 7777.77, Status.BUSY),
            new Employee(104, "赵六", 8, 7777.77, Status.FREE),
            new Employee(104, "赵六", 8, 7777.77, Status.FREE),
            new Employee(105, "田七", 38, 5555.55, Status.BUSY)
    );

    //3. 终止操作
	/*
		归约
		reduce(T identity, BinaryOperator) / reduce(BinaryOperator) ——可以将流中元素反复结合起来，得到一个值。
	 */
    @Test
    public void test1() {
        List<Integer> list = Arrays.asList(1, 2, 3, 4, 5, 6, 7, 8, 9, 10);

        Integer sum = list.stream()
                .reduce(0, (x, y) -> x + y);

        System.out.println(sum);

        System.out.println("----------------------------------------");

        Optional<Double> op = emps.stream()
                .map(Employee::getSalary)
                .reduce(Double::sum);
        Double a = 0.0;
        for (Employee e : emps) {
            a += e.getSalary();
        }
        System.out.println(a);
        System.out.println(op.get());
    }

    //需求：搜索名字中 “六” 出现的次数
    @Test
    public void test2() {
        Optional<Integer> sum = emps.stream()
                .map(Employee::getName)
                .flatMap(LearnStreamaAPI3::filterCharacter)
                .map((ch) -> {
                    if (ch.equals('六'))
                        return 1;
                    else
                        return 0;
                }).reduce(Integer::sum);

        System.out.println(sum.get());
    }

    public static Stream<Character> filterCharacter(String str) {
        List<Character> list = new ArrayList<>();

        for (Character ch : str.toCharArray()) {
            list.add(ch);
        }

        return list.stream();
    }

    //collect——将流转换为其他形式。接收一个 Collector接口的实现，用于给Stream中元素做汇总的方法
    @Test
    public void test3() {
        List<String> list = emps.stream()
                .map(Employee::getName)
                .collect(Collectors.toList());

        list.forEach(System.out::println);

        System.out.println("----------------------------------");

        //TODO Set集合 去重哦
        Set<String> set = emps.stream()
                .map(Employee::getName)
                .collect(Collectors.toSet());

        set.forEach(System.out::println);

        System.out.println("----------------------------------");

        HashSet<String> hs = emps.stream()
                .map(Employee::getName)
                .collect(Collectors.toCollection(HashSet::new));

        hs.forEach(System.out::println);
    }

    @Test
    public void test4() {
        //根据比较器选择最大的
        Optional<Double> max = emps.stream()
                .map(Employee::getSalary)
                .collect(Collectors.maxBy(Double::compare));

        System.out.println(max.get());

        //根据比较器选择最小的
        Optional<Employee> op = emps.stream()
                .collect(Collectors.minBy((e1, e2) -> Double.compare(e1.getSalary(), e2.getSalary())));

        System.out.println(op.get());

        //属性值求和
        Double sum = emps.stream()
                .collect(Collectors.summingDouble(Employee::getSalary));

        System.out.println(sum);

        //属性值平均值
        Double avg = emps.stream()
                .collect(Collectors.averagingDouble(Employee::getSalary));

        System.out.println(avg);

        //流中元素的个数
        Long count = emps.stream()
                .collect(Collectors.counting());

        System.out.println(count);

        System.out.println("--------------------------------------------");

        //收集流中属性的统计值
        DoubleSummaryStatistics dss = emps.stream()
                .collect(Collectors.summarizingDouble(Employee::getSalary));

        System.out.println(dss.getMax());
    }

    //分组
    @Test
    public void test5() {
        Map<Status, List<Employee>> map = emps.stream()
                .collect(Collectors.groupingBy(Employee::getStatus));

        System.out.println(map);
    }

    //多级分组
    @Test
    public void test6() {
        Map<Status, Map<String, List<Employee>>> map = emps.stream()
                .collect(Collectors.groupingBy(Employee::getStatus, Collectors.groupingBy((e) -> {
                    if (e.getAge() >= 60)
                        return "老年";
                    else if (e.getAge() >= 35)
                        return "中年";
                    else
                        return "成年";
                })));

        System.out.println(map);
    }

    //分区
    @Test
    public void test7() {
        Map<Boolean, List<Employee>> map = emps.stream()
                .collect(Collectors.partitioningBy((e) -> e.getSalary() >= 5000));

        System.out.println(map);
    }

    //拼接
    @Test
    public void test8() {
        String str = emps.stream()
                .map(Employee::getName)
                .collect(Collectors.joining(",", "----", "----"));

        System.out.println(str);
    }

    @Test
    public void test9() {
        Optional<Double> sum = emps.stream()
                .map(Employee::getSalary)
                .collect(Collectors.reducing(Double::sum));

        System.out.println(sum.get());
    }

}
